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Feeder Size Calculator

Formula

The formula to calculate the feeder size is:

$FS = \frac{2 \cdot \rho \cdot I}{V \cdot PF}$

Where:

$FS$ is the feeder size (circular mils).
$\rho$ is the resistivity of the conductor material (ohms per circular mil foot).
$I$ is the current (amperes).
$V$ is the voltage (volts).
$PF$ is the power factor (dimensionless).

Example

Let's say the resistivity ( $\rho$ ) is 10 ohms per circular mil foot, the current ( $I$ ) is 100 amperes, the voltage ( $V$ ) is 240 volts, and the power factor ( $PF$ ) is 1. Using the formula:

$FS = \frac{2 \cdot 10 \cdot 100}{240 \cdot 1}$

We get:

$FS = \frac{2000}{240} \approx 8.33 \text{ circular mils}$

So, the feeder size ( $FS$ ) is approximately 8.33 circular mils.

What is Feeder Size?

Feeder size refers to the cross-sectional area of an electrical feeder wire, which is necessary to carry a certain amount of current without overheating or dropping too much voltage. It is typically measured in circular mils, which is a unit of area used specifically for wires. Proper feeder sizing is crucial for the safety and efficiency of an electrical system.